A backcountry fire ignited by lightning in Yellowstone National Park is up to 250 acres and growing in the direction of the Grand Loop Road, prompting firefighters to take to the air Friday with water-dropping helicopters.

The fire, dubbed "Arnica" for a creek on the west side of Yellowstone Lake, is burning in lodgepole pine forest. According to a release from the park, the fire "continues pushing to the south toward the power line and the Grand Loop Road. Helicopters will be using bucket drops to cool off the southern head and the west flank of the fire to keep it away from the road and power line corridor."

"Smoky conditions are present and expected to continue during the afternoon peak burning period," the release added. "Visitors are reminded to reduce driving speeds due to smoke along the roadways. No road closures are anticipated at this time."

Windy conditions were expected to push the fire to the southwest, and the warm temperatures and low humidity level will work against suppression efforts. For visitors in the park, the fire provides an up-close picture of nature at work.

"Smoke and flames will be visible from the Grand Loop Road. Check at park visitor centers or backcountry offices for the current status of hiking trails and backcountry campsites in the area. No sites or facilities are currently closed due to fire activity," park officials said at mid-day Friday.